Telephone-exchange system.



J. L. WRIGHT.

TELEPHONE EXCHANGE SYSTEM.

APPLICATION FILED OCT. 31. 1914.

1- 1,2 Patented Apr. 3, 1917.

2 SHEETS--SHEET WITNESSES:

Maw

L L. WRiGHT.

TELEPHONE EXCHANGE SYSTEM. APPLICATION FILED OCT. 31. 1914.

Patented Apr. 3, 1917.

2 SHEETS-SHEET 2 WI TNESSES:

MM mj M mm JOSEPH L. WRIGHT, OF CLEVELAND, OHIO, ASSIGNOR, BY MESNE ASSIGNMENTS, TO WESTERN ELECTRIC COMPANY, INCORPORATED, A CORPORATION OF NEW YORK.

TELEPHONE-EXCHANGE SYSTEM.

Specification of Letters Patent.

Patented Apr. 31., Milt.

Application filed October 31, 1914. Serial No. 869,670."

and useful Improvements in Telephone-Ere change Systems, of which the following is a specification.

My invention relates to telephone exchange systems employing automatic switching mechanism for interconnecting subscribers lines and is applicable to said systems whether of the full automatic or semi-automatic types.

The manner in which the automatic switching mechanism is controlled allows what are termed two-wire or metallic circuits to be used. In systems employing such circuits it has been customary to employ a combination of slow and quick acting relays. These relays are responsive to current changes in the metallic circuits and control the automatic switching mechanism for cffecting connection between subscribers lines.

With my invention no slow acting relays or retarded devices are used. The current impulses for controlling the automatic switching mechanism are alternating in character. These impulses are transmitted by means of an alternating current device so arranged to allow impulses of different frequencies to be transmitted for directing the action of the automatic switching mechanism.

The automatic switching mechanism. is provided with receiving devices responsive to the impulses transmitted and inacting control the automatic switching mechanism.

For purpose of illustration I have shown selector and coi'inector switches of the type shown in Patent No. 815,321 to Keith and Erickson. March 13, 1906, and Patent No. 815,176 to Keith and Erickson, March 13, 1906.

My invention is illustrated in the accompanying drawings wherein:

Figure 1 shows a subscribers line equipment and a first selector circuit.

Fig. 2 shows a connector circuit.

Fig. 3 shows a form of dial to be used with the signal device.

Referring to Fig. 1, the subscribers station at AA is provided with apparatus usual in common battery systems, and in addition is provided with an alternating current transmitting device 100 shown in the form of a standard type hand generator. In or: der to cause the proper number of impulses to be transmitted to direct the movement of the automatic switches the dial or handle is moved around to transmit the proper number of impulses. In case five impulses are to be transmitted the dial is moved so as to cause five impulses tobe transmitted. After the predetermined impulses are transmitted the dial or handle is rapidly revolved to cause a "series of alternations of high frequency to be transmitted to the automatic switches.

The number of directive impulses are de termined by placing the finger in the proper opening or window and pulling the dial around until the stop is engaged. The numbers are back of the openings and do not move with the dial. The movement of the dial can be retarded in any well known manner so that extra care need not be taken when operating. It is onl necessary that the directive impulses are 0 a frequency low enough so as not to operate the high frequency relays or devices associated with the automatic switches.

The directive or low frequency impulses correspond to the so-called vertical impulses in the well known Strowger system, while the high frequency impulses correspond to the rotary impulses. The low frequency impulses for predeterminedly operating the automatic switches cause the operation of a tuned polarized relay B. The operation of this relay in turn completes the circuit of the vertical magnet causing the first selector switch J to step vertically.

The l'ii'gh frequency impulses or alternations causing the operation of a. polarized rclay C tuned to respond to these frequencies but not to the low frequency current. This relay serves to cause the shifting of the switch: circuit in certain order.

In order to transmit the impulses the receiver is removed from the hook and then the impulse device operated. This device in operating closes the contact springs 101 and 103 but breaks the contact springs 102 and 103, the effect being that the generator or impulse device is connected across the tip set is disconnected therefrom.

Referring to Fig. 2, the connector switch is shown at W. The low frequency polarized relay L in operating causes the impulses to be transmitted to the vertical and rotary magnets. The operation of the high frequency polarized relay M changes the circuit conditions and allows the various magnets and other circuits to be shifted in a certain order.

In connection with the switch W I have provided an extra side switch arm Z for the purpose of connecting the ringing relay R at the proper time. Relay K remains energized over the line of the calling subscriber while the receiver is removed or while the impulse device is being operated.

The operation of the system is as follows: The subscriber at station AA desiring to call another subscriber first removes his receiver. The removal of the receiver causes the energization of relay A. The operation of this relay partially completes the circuit of the vertical magnet F so that it can be controlled by the operation of relay B and also grounds the test contacts whichappear in its group of connector switches. The subscriber in operating the signaling device 100 causes the first set of impulses to be transmitted and to operate relay B. The operation of this relay completes the circuit of the vertical magnet F by the following path: ground, contacts of relay B, 9, contacts of relay A, 10, contacts of relay D, 11, winding of magnet F to battery BB. The operation of the magnet F causes the switch J to step vertically and bring the wipers 25, 26 and 27 in line with the proper row of contacts. After the first set of directive impulses have been transmitted the high frequency impulses are transmitted by the device 100, thereby causing the operation of relay 0. The operation of this relay completes the circuit of the private relay D. The operation of relay D causes the side switches to step to the second position, thereby connecting the winding of relay D in series with the winding of the trunk release relay E. While these windings are in series relay D is operated but relay E, as is customary, is so adjusted as not to operate at this time. These relays will remain in series and relay 1) energized until the test wiper 27 engages an idle contact or one free from ground. As soon as such a contact is found then relay 1) becomes dot-Energized and the side switches step to the third position. In taking this third position the trunk conductors are extended 'to the wipers 25 and 26 respectively and ground connected directly to the winding of relay E. Ground being connected in this manner renders the test contact engaged by the wiper 27 busy against other calls.

The operation of the side switch arm 300 connects ground to the test contact 19 after relay A becomes disconnected by the side switches moving to the third position. Ground maintained in this manner renders the calling line busy against other calls and also operates relayI.

The calling subscriber is now connected to an idle connector such as shown in Fig. 2. As soon as such a connector is engaged then relay K becomes energized over the calling subscribers line circuit while relay becomes energized in series with the winding of the relay E and the resistance coil -13. The winding of this coil is of comparatively high resistance so as to prevent the operation of relay E. Relay 0, however, is so adj usted that it will operate in series with relay E and the resistance 43.

The subscriber at station AA now operates the transmitting device and causes the second series of directive impulses to be transmitted to the connector switch, thereby operating the polarized relay L. The operation of this relay completes the circuit of the vertical magnet T by the following path; ground, contacts of relay L, 56, contacts of relay N, 57, side switch, 58, winding of magnet T to battery BB. The operation of the magnet T causes the switch W to step yertically and bring its wipers 35, 45 and 50 in line with the proper row of contacts.

After the second series of impulses have been transmitted a series of high frequency impulses are then transmitted, thereby operating relay M. The operation of thisrelay completes the circuit of the private relay N causing the side switches to step to their second position. The calling subscriber then causes the third set of directive impulses to be transmitted thereby operating relay L. The operation of this relay at this time completes the circuit of the rotary magnet U as the vertical magnet T was disconnected when the side switches moved to the second position. The third series of impulses causes the switch \V to bring the wipers to rest on contacts associated with the called-for line.

A series of high frequency impulses are next transmitted at the calling station thereby causing the operation of relay M. The operation of this relay again completes the circuit of the irivate relay N. The operation of relay at this time connects the test relay S to the test wiper 50 by the following path: battery BB, winding of relay S. (55, contacts of relay N, 64, side switch, (33. test wiper 50. In case the called-for line is busy, ground will be connected to the test contact thereby operating relay S. The operation of this relay completes the circuit of the release magnet V causing the restoration of the switch \V. This relay S remains locked to ground through the contacts of relay O. The operation of relay S connects a suitable busy tone test or signal to the trunk conductor, thus notifying the calling subscriber that the called-for line is busy.

In case, however, the called-for line is not busy relay S will not be affected and the switch wipers will remain in engagement with the contacts of the called-for line and the side switches will step to the third position, thereby connecting the trunk conductors to the wipers 35 and 45 respectively. The operation of the side switches also causes ground to be connected directly to the test wiper 50, thusrendering the called line busy against other calls.

At the final step of the side switch Z the circuit of the ringing relay R is completed as follows: ground, commutator Y, winding of the relay R, 71, contacts of relay X, 70, Z to battery BB. Relay R is operated intermittently by means of the commutator Y and applies generator current to the called line.

During a non-ringing period when relay R is denergized and the receiver at the called station removed then relay P is operated. The operation of this relay completes the circuit of relay X, which remains locked to ground through the cam springs 55. The operation of relay X opens the circuit of the ringing relay R, thus preventing further application of generator current. The operation of relay X also connects ground through the resistance coil 42 to the test contact engaged by the test wiper of the first selector switch. The object of this ground connection is to render the connector switch busy against other calls in case the calling subscriber should re )lace his receiver before that of the called su scriber.

At the termination of the conversation the called subscriber in replacing his receiver causes relay P to restore. This relay in restoring completes the circuit of the release magnet V by the following path: ground, contacts of relay P, 62, contacts of relay X, 48, winding of magnet V to battery BB. The operation of this ma net causes the res toration of the switch I As soon as this switch restores the cam springs 55 are opened, thereby removing ground from the locking contact of relay X, allowing it to restore.

The calling subscriber replacing his receiver causes relay K to restore. The restoration of this relay causes battery to be intermittently connected between the Winding of relay 0 and the coil 43 by means of the commutator 200. When battery is connected in this manner the coil 43 is shunted, allowing relay E to be operated in series with the winding of relay 0, thereby causing relay E to attract its armature and complete the circuit of the release magnet H of the switch J. After this battery connection is removed by the action of the commutator 200 then relay E becomes deenergized and opens the circuit of the magnet H, thereby allowing the switch J to restore. As soon as the wiper 27 disen ages the test contact then relay 0 becomes eenergized and the intermittent shunt is removed from the coil 43.

It will be noted that when the called subscriber answers he retains control of the connector switch and causes its release when replacing his receiver.

In case, however, the called subscriber does not respond then the calling subscriber controls the release of the connector switch as well as the release of the first selector switch. In this event the release of the connector switch is effected by the action of relay K which in restoring completesthe circuit of the release magnet V by the following path: ground, cam springs 55, 46, contacts of relay K, 47, contacts of relay X, 48, winding of magnet V to battery BB.

While I have shown the signaling or transmitting device in the form of a hand generator, the speed being controlled by the subscriber, it of course follows that this device can be so constructed that the speed is auto matically regulated.

In automatic systems it is common practice to have the dial or signalin device transmit the impulses in restoring, t e speed in restoring being controlled by suitable gears and governor.

In connection with Fig. 1 I have shown an impedance or resistance coil 105 bridged across the conductors connected to contacts 102 and 103. This coil is simply used as an alternative and can be omitted if desired. Its function is merely to allow the telephone set at thesubscribers instrument to remain in circuit with the line in series with the winding of the coil 105. The impedance of this coil would be such that the current generated by the device 100 would not be shunted and prevent the operation of the tuned relays.

While I have shown but one impulse device or generator for transmitting currents of different frequencies it of course follows that one generator can be applied for each frequency.

Having thus described my invention what I desire to secure by Letters Patent is:

1. In a telephone exchange 5 stem, subscribers lines, connective means .or the lines, means at the subscribers stations to produce alternating current impulses of relatively low frequency for operating said connective means, additional means at the subscribers stations to produce alternating current impulses of relatively high frequency, to produce changes in the circuits of the connective means, substantially as set forth.

2. In a telephone exchange system, the combination with an automatic switch, of an alternating current signaling device for controlling the operation of said switch, two conductors extending from said device to said switch normally closed during the opthe operation of said switch, substantially as set forth.

3. In a telephone exchange system, the combination with. an automatic switch, of two conductors extending to said switch having an associated alternating current signaling device, means associated with said switch and responsive to the operation of said signalingdevice for controlling the action of said switch, said conductors being closed during the operation of said signaling device, substantially as set forth.

4. In a telephone exchange system, automatic switching mechanism and metallic line circuits, of devices associated with said automatic switching mechanism adapted to respond to-alternating currents of different frequencies, means at the subscribers stations to operate said devices over said line circuits to determine the positions to be assumed by said automatic switching mechanism, substantially as set forth.

5. In a telephone exchange system, the combination with an automatic switch, of an alternating current signaling device for controlling the operation of said switch, two conductors extending from said device to said switch normally closed during the operation of the signaling device and during the operation of the said switch, releasing means associated with said switch rendered operable when said conductors are opened, substantially as set forth.

6. In a telephone exchange system, the combination with an automatic switch, of two conductors extendin to said switch, 01 an alternating current signaling device for controlhng said switch over said conductors while said conductors are closed, releasing means for said switch controlled by the opening of said conductors, substantially as set forth.

7. In a telephone exchange system, the combination with a traveling automatic switch, actuating means for said switch responsive to alternating current impulses, releasing means for said switch, said releasing means being unresponsive to said impulses, substantially as set forth.

8. In a telephone exchange system, the combination with calling and called subscribers lines, of traveling automatic switches for interconnecting said lines, means associated with each of said automatic switches and responsive to alternating currents of different frequencies for actuatim said automatic switches to interconnect sai lines, of releasing means associated with said automatic switches unresponsive to said alternating currents for releasing said automatic switches, substantially as set forth.

9. The combination with an automatic switch, actuating means for said switch, shifting means for said switch, releasing means for said switch, a control circuit, additional individual means in said circuit as sociated with each of said means and directly responsive to current changes over said circuit for controlling said switch, substantially as set forth.

10. In a telephone exchange system, the combination with an automatic switch, an alternating current signal device, of a relay associated with said switch and responsive to alternating currents of a low frequency for directively operating said switch, of a second relay responsive to currents of higher frequency for controlling the shifting means of said switch.

In testimony whereof I aiiix my signature presence of two witnesses.

JOSEPH L. WRIGHT.

Witnesses:

E. L. GREENEWALD, ADA DEHN. 

